Electroscopic powder feeding apparatus utilizing rotating helical members

ABSTRACT

The toner feed apparatus comprises two oppositely wound spring members which are concentrically mounted. The spring members are driven so that the pitch of the outside spring conveys the toner toward a perforated end plate which feeds toner into the developer system. The inside spring is wound in the opposite direction so that contaminating material which does not pass through the perforated end plate is conveyed back and out of the toner feed apparatus for collection.

United States Patent 1 1 Stauffer I [54] ELECTROSCOPIC POWDER FEEDING APPARATUS UTILIZING ROTATING HELICAL MEMBERS [75] Inventor: Russell A. Stautfer, San Jose, Calif.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: Mar. 30, 1971 [21] Appl. No.: 129,432

[52] US. Cl ..222/240, 118/637, 222/DIG. l [51] Int. Cl. ..B67d 23/00 [58] Field'of Search ..222/l89, DIG. l, 240, 241;

[56] References Cited UNITED STATES PATENTS 3,439,836 4/1969 Ricciardi ..222/240 1 51 Apr. 3, 1973 3,224,649 12/1965 Gunto ..222/D1G. 1 3,310,205 3/1967 Meyer ..222 412 x 3,272,397 9/1966 Bean ..222 1s9 x Primary Examiner-Stanley I-I Tollberg Attorney-Hamlin & Jancin and Otto Schmid, Jr.

The toner feed apparatus comprises two oppositely wound spring members which are concentrically mounted. The spring members are driven so that the pitch of the outside spring conveys the toner toward a perforated end plate which feeds toner into the developer system. The inside spring is wound in the opposite direction so that contaminating material which does not pass through the perforated end plate is conveyed back and out of the toner feed apparatus for collection.

ABSTRACT 11 Claims; 6 Drawing Figures PATENTEDAPR3 I975 3.724.725

' SHEET 1 OF 2 INVENTOR I RUSSELL A. STAUFFER B wmy ATTORNEY PATENTEDAPR 3 H175 SHEET 2 OF 2 CL 0 CH TONER CONCENTRATION STOP v START v VOLTAGE FIG.5

ELECTROSCOPIC POWDER FEEDING APPARATUS UTILIZING ROTATING HELICAL MEMBERS BACKGROUND OF THE INVENTION troscopic toner is combined with a suitable carrier material to form electrophotographic developer, and

the carrier material has a suitable covering which im- I parts the necessary triboelectric properties to attract toner to and be carried by the carrier material. The carrier material in the developer does not adhere to either the charged or uncharged areas of the electrophotographic plate whereas the toner particles which are carried by the carrier material are attracted to and retained by electrically charged plate areas as the developer is cascaded across the plate surface. A quantity of toner sufficient to replace the toner which goes to make up the printed image is then added to the developer and the developer is recirculated to produce further printed images on a continuous basis.

To maintain a good quality printed image, the balance between the quantity of electroscopic toner and the carrier in the developer must'be closely controlled. The extreme difficulty in handling electroscopic toner is well known to those skilled in the electrophotographic printing art. This difficulty is caused by the fact that toner particles per se are extremely small and therefore difficult to dispense in accurately metered quantities. In addition, the toner is a tacky substance which tends to cake and clump when being dispensed and this characteristic is variable with changes in temperature and humidity. A further dif ficulty is caused by the fact that the toner is fused by either heat or pressure or by combinations of heat and pressure and this characteristic limits the manner by which the toner can be handled.

The problem is compounded in an application such as a computer output printer in which printing is accomplished at several thousand lines a minute, since in a system of this nature, the quantity of electroscopic toner used is greatly increased over prior art systems. For this reason, the dispenser must maintain positive control over the toner being metered at all times. It is therefore the major object of this invention to provide an electroscopic toner dispenser capable of feeding an accurately controlled quantity of toner on a continuous basis.

A system which produces printing at a high rate consumes a large quantity of electroscopic toner. The toner that is not transferred to the print sheet is cleaned from the electrophotographic plate prior to the next printing cycle. Even though the percentage of toner transferred to the print sheet is high, the quantity of toner removed in the cleaning station is substantial. From the standpoint of both cost considerations and disposal considerations, it is desirable to permit re-use of the toner removed at the cleaning station. This has not been possible on a reliable basis in the past without an intermediate step to remove contaminating material such as paper fibers and cleaning brush fibers.

It is therefore a further object of this invention to provide a toner dispensing apparatus capable of reliably feeding re-used toner without an intermediate processing step.

SUMMARY OF THE INVENTION Briefly, according to the invention there is provided toner feeding apparatus having a hopper portion and a toner outlet portion terminated by a perforate output member, a pair of oppositely wound helical spring members mounted concentrically on a support member for rotation within the toner outlet portion of the compartment and drive means is provided to rotatably drive the support member so that the first helical spring member feeds toner from the hopper portion toward and through the outlet member to a developer apparatus and the second helical spring member feeds contaminant material in the opposite direction for disposal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a typical electrostatic printer incorporating the developing apparatus of the invention;

FIG. 2 is a side elevation view of the toner feeding apparatus of the invention shown partially in section to provide an understanding of its structure;

FIG. 3 is a perspective view of the toner feed apparatus according to the invention;

FIG. 4 is a section view along the lines 4-4 of F IG.'

FIG. 5 is a plot of output voltage vs. toner concentration.

FIG. 6 is an alternate embodiment of the drive means for the toner feeding apparatus of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, the relationship between the toner feeding apparatus and a typical electrostatic printer is shown schematically in FIG. 1. In this apparatus a rotatable drum 10 carries around its periphery an electrophotographic photoconductive member 12 on which is directed an image which it is desired to reproduce on a recording sheet. The surface of the photoconductor is uniformly charged to a predetermined polarity by suitable means such as a corona discharge device, and a suitable exposure means is operable to direct the image to be copied onto the surface of the photoconductor, thereby producing a charged pattern in the form of the image to be copied.

, Thereafter the drum passes a development station 14 at into the reservoir 16. A copy paper is fed into contact with the developed electrostatic image and the toner is attracted to the sheet by suitable means such as a corona discharge device having a polarity opposite that of the toner thereby attracting the toner to the copy sheet. The sheet is separated from the drum and fed past a fusing station which serves to fuse and permanently fix the toner to the paper. Since transfer of all the image toner is not usually accomplished, the residual toner is cleaned from the surface of the photoconductor by a suitable cleaning apparatus. This operation completes the cycling of the drum for reproducing the desired image.

In accordance with the present invention, the developer apparatus maintains the proper balance between the quantity of electroscopic toner and the carrier in the xerographic developer so that uniform quality copies result. This is accomplished by replacing the quantity of toner which goes to make up the imprint on the printed record. The developer apparatus comprises a carousel drum conveyor 18 which functions to continually recirculate the developer material from the reservoir portion 16 to chute member which serves to direct the developer material over the drum surface for development of the electrostatic image. Drum conveyor 18 is rotated about an axis substantially perpendicular to the surface of drum 10. The inner surface of the periphery of drum 18 has a frictional surface so that developer material is engaged from the reservoir portion 16 and conveyed to the top of the drum at which time gravity causes the developer material to cascade across chute 20 and thence across the surface of the drum to develop the image. A small quantity of the developer material cascading across chute 20 is directed to the toner concentration sensor means 29. Sensor means 29 produces an electrical signal on line 21 proportional to the percentage of toner present in the developer material. A toner feed apparatus 22 is provided to replenish the toner utilized from the developer material during the printing operation in response to a signal generated by control means 25.

The toner feeding apparatus 22 comprises a toner drive portion 24 and a toner supply portion 27. Toner supply member 27-comprises an enclosed container which holds a substantial supply of toner which is mounted for gravity feeding of toner to toner drive means 24. Toner feed apparatus is driven by drive means 23 through suitable gears or belts. Drive means 23 comprises any suitable drive capable of continuous control by the use of electrical signals such as an electric motor. Control means utilizes the output from toner concentration sensor 29 to generate asuitable control signal for control of drive means 23.

A typical output signal from toner concentration sensor means 29 is shown in FIG. 5. For proper operation of the printer system the toner concentration must be maintained accurately to an optimum concentration C,,. The toner concentration is the proportion of toner on a weight basis in the developer mix. The maximum allowable tolerance is shown as C for the low tolerance and C H for the high tolerance. A typical control for a printer system would be a toner concentration of 0.8% i 0.1. Voltages V and V correspond to the output voltage corresponding to the two extremes of the allowable variation of toner concentration. However, the precise circuits that are used to obtain this output signal is determined by the type of toner concentration sensor used. A number of sensors are known which sense in some physical quantity such as inductance, capacitance, resistance etc. as a function of toner concentration. The output which represents the variation of the quantity being sensed is then converted to an output as shown in FIG. 5 by suitable techniques such as applying the output to a bridge circuit and providing sufficient amplification to control drive means 23.

Drive means 23 may comprise any suitable drive source such as a variable speed motor, for example. In this case, control means 25 utilizes the output from sensor 29 to generate signals of sufficient power and magnitude to control drive means 23. In this mode of control it is desired to maintain the drive means OFF when the concentration reaches C in FIG. 5 and for all high concentrations. The drive means is then turned ON for concentrations less that C and the drive means is driven faster as the concentration decreases from C This type of control can be accomplished by commercially available controls, and control is accomplished by turning the drive means ON when a voltage less than voltage V corresponding to concentration C is sensed and utilizing a voltage proportion to the difference between the sense voltage and V for field control of the variable speed drive means.

Control over toner feeding can also be exercised in the embodiment shown in FIG. 6 by a clutched drive. In this embodiment drive means 23' comprises a substantially constant speed motor which is connected by suitable belts of gears to drive the toner feeding means. A clutch member 64 is provided to selectively couple drive means 23' for driving the toner feeding means. Clutch member 64 comprises any suitable clutch apparatus which can be selected for power transmission in response to an electrical signal. Control is accomplished by control means 25' by generating a signal for actuating the clutch in response to sensing a voltage level V in FIG. 5 and generating a signal for de-energizing the clutch member 64 in response to sensing a voltage level V H in FIG. 5.

Referring to FIGS. 2 and 3, the toner drive means comprises a first helical spring drive member 28 and a second helical spring drive member 30. Spring members 28 and 30 are mounted within toner compartment 32. Toner compartment 32 comprises a hopper portion 34 and a toner outlet portion 36. Spring members 28 and 30 are supported at one end by support and drive member 38. The spring members then extend substantially under the hopper portion 34 and along the toner outlet portion 36 to toner outlet member 40. Spring member 28 is wound in a clockwise direction as viewed from output member 40 so that when member 38 is driven by suitable drive means 42 in a clockwise direction, toner is taken from hopper portion 34 and advanced by spring member 28 along toner outlet portion 36 and through output member 40. Any toner that is not forced through output member 40 is moved counter to the direction of flow by spring member 30 which is wound in a counter clockwise direction as view from output member 40. This action prevents caking or compacting of toner in the process of feeding toner through output member 40. Contaminating materials that are too large to pass through the perforations in output member 40 work their way to the center of spring member 30 and are carried counter to the normal flow of toner. As the contaminating material tumbles through the helix of spring member 30, it becomes disassociated with the toner and is eventually forced through the hollow center of member 38 intoa collecting container 44.

In the embodiment shown spring members 28 and 30 are supported by member 38. Member 38 comprises a cylindrical drum portion of a dimension so that the inner diameter of spring member 28 engages the outer surface 46 of the drum portion in a force-fit and the outer diameter of spring member 30 engages the inner surface 48 in a force-fit. Spring member 28 then extends into toner outlet portion 36 with sufficient clearance in the cylindrical passage so that the frictional heat generated will not be sufficient to damage the thermoplastic toner. Spring member 28 should be of sufficient length that a slight compression results, in the nature of 3 to 5 percent when the spring member is in position, as a result of the support provided by member 38 on one end and extending along toner outlet portion 36 to outlet member 40 on the other end. The end of spring member 30 extends close to outlet member 40 but this end of spring member 30 is unsupported. This mounting prevents caking of toner during a feeding operation due to the flexibility of spring member 30. The perforations in outlet member 40 are chosen a suitable size to prevent toner, from exiting when the drive means is OFF and to provide an exit for toner to the developer apparatus when the drive is ON. A number of factors including the toner particle size, the feed rate etc. are considered in determining this size. In a particular embodiment spring member 28 had an outside diameter of about 1 inches and a clearance of about 0.045 on a side within toner outlet portion 36. In this case, the perforations in outlet member 40 were about 0.050 diameter and the number of perforations caused member 40 to be about 28 percent open. 1

Due tothe high speed of the electrostatic printer for which the developer assembly is designed to work, it is desireable to install a relatively large supply of toner in the machine while the machine is running. The apparatus shown in FIGS. 3 and 4 permits the loading of toner into the machine while the machine is running without adversely affecting the operation of the machine. Supply portion 34 of the toner feed means is supply. Shutter member 50 is mounted in an upper housing 52 which is hinged for pivotal movement about one edge. Retaining springs 54 are provided to latch housing member 52 in position for feeding toner into hopper portion 34 of the lower toner compartment 32. To prevent accidental spillage of toner, an interlock is provided on shutter member 50 so that the shutter cannot be opened until the housing 52 is latched into place and the housing cannot be unlatched untilthe shutter member 50 is fully closed.

. As shown in FIG. 4, the shutter member 50 is locked in the closed full line position when the housing member 52 is latched into position. To disengage latch members 54 to unlatch housing member 52, shutter member is moved to the fully inserted position (dotted to the left in FIG. 4) at which position the shutter member is effective to disengage latch members 54. Shutter member 50 is then retained in the closed position by interlock means until housing member 52 is again latched into position. Shutter member 50 can then be withdrawn to the fully open position (dotted to the right in FIG. 4).

In the embodimentshown the interlock means comprises a pair of interlock springs 56 which are mounted to' engage interlock openings 58in shutter member 50. When retaining springs 54 are engaged, release pins 60 engage interlock springs 56 to deflect the springs sufficiently so that movement of shutter member 50 cams the springs away to permit movement of shutter member 50 to a fully open position so that toner from toner supply container 27 flows freely into toner compartment 32. Retainer springs 62 are provided to limit the motion of shutter member 50 to the fully open position.-'

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in the form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is: r

1. Apparatus for feeding electroscopic toner to a utilization device comprising:

a toner compartment having a toner outlet portion;

an output member having a plurality of small holes therein mounted for conveying toner from said toner outlet portion to said utilization device;

a first flexible helical member formed in a first sense;

a second flexible helical member formed in a sense opposite to said first sense; said second helical member being positioned concentrically within said first helical member;

a support member for supporting one end of each of said helical members so that said helical members extend along said toner outlet portion to said output member; and

drive means for rotating said support member so that said first helical member feeds toner toward and through said output member to said utilization device.

2. The toner feeding apparatus according to claim 1 additionally comprising:

means for selectively controlling said drive means to maintain a predetermined concentration of toner in said utilization device.

3. The toner feeding apparatus according to claim 1 additionally comprising:

speed control means for controlling the rotational speed of said drive means so that the quantity of said toner metered to said utilization device may be regulated accordingly.

4. An electroscopic toner feeding apparatus for feeding toner to a developer apparatus, comprising:

a toner compartment having a hopper portion and a toner outlet portion;

an output member having a plurality of small holes therein mounted at one end of the toner outlet portion of said compartment;

a first helical spring member positioned for rotation within the toner outlet portion of said compartment;

a second helical spring member positioned concentrically within said first helical spring member for rotation along with said first spring member;

a support member for supporting one end of each of said helical spring members so that said helical spring members extend along said toner outlet portion of said compartment to said output member; and

drive means for rotating said support member so that said first helical spring member feeds said toner toward and through said output member to said developer apparatus.

5. The toner feeding apparatus according to claim 4 additionally comprising:

means for selectively controlling said drive means to maintain a predetermined concentration of toner in said developer unit.

6. The toner feeding apparatus according to claim 4 additionally comprising:

speed control means for controlling the rotational speed of said drive means so that the quantity of said toner metered to said developer unit may be regulated accordingly.

7. The toner feeding apparatus according to claim 4 additionally comprising:

a shutter member to close said hopper portion during replacement of toner supply operations; and

interlock means to prevent opening of said shutter member during said toner supply replacement operation.

8. The toner feeding apparatus according to claim 1 additionally comprising:

means for deriving a signal proportional to the concentration of toner in said utilization device; and means for selectively controlling said drive means in response to said signal to maintain a predetermined concentration of toner in said utilization device.

9. The toner feeding apparatus according to claim 1 additionally comprising:

means for deriving a signal proportional to the concentration of toner in said utilization device; and speed control means for controlling the rotational speed of said drive means in response to said signal so that the quantity of said toner metered to said utilization device may be regulated accordingly. 10. The toner feeding apparatus according to claim 4 additionally comprising:

means for deriving a signal proportional to the concentration of toner in said developer unit; and means for selectively controlling said drive means in response to said signal to maintain a predetermined concentration of toner in said developer unit.

speed control means for controlling the rotational speed of said drive means in response to said signals so that the quantity of said toner metered to said developer unit may be regulated accordingly. 

1. Apparatus for feeding electroscopic toner to a utilization device comprising: a toner compartment having a toner outlet portion; an output member having a plurality of small holes therein mounted for conveying toner from said toner outlet portion to said utilization device; a first flexible helical member formed in a first sense; a second flexible helical member formed in a sense opposite to said first sense; said second helical member being positioned concentrically within said first helical member; a support member for supporting one end of each of said helical members so that said helical members extend along said toner outlet portion to said output member; and drive means for rotating said support member so that said first helical member feeds toner toward and through said output member to said utilization device.
 2. The toner feeding apparatus according to claim 1 additionally comprising: means for selectIvely controlling said drive means to maintain a predetermined concentration of toner in said utilization device.
 3. The toner feeding apparatus according to claim 1 additionally comprising: speed control means for controlling the rotational speed of said drive means so that the quantity of said toner metered to said utilization device may be regulated accordingly.
 4. An electroscopic toner feeding apparatus for feeding toner to a developer apparatus, comprising: a toner compartment having a hopper portion and a toner outlet portion; an output member having a plurality of small holes therein mounted at one end of the toner outlet portion of said compartment; a first helical spring member positioned for rotation within the toner outlet portion of said compartment; a second helical spring member positioned concentrically within said first helical spring member for rotation along with said first spring member; a support member for supporting one end of each of said helical spring members so that said helical spring members extend along said toner outlet portion of said compartment to said output member; and drive means for rotating said support member so that said first helical spring member feeds said toner toward and through said output member to said developer apparatus.
 5. The toner feeding apparatus according to claim 4 additionally comprising: means for selectively controlling said drive means to maintain a predetermined concentration of toner in said developer unit.
 6. The toner feeding apparatus according to claim 4 additionally comprising: speed control means for controlling the rotational speed of said drive means so that the quantity of said toner metered to said developer unit may be regulated accordingly.
 7. The toner feeding apparatus according to claim 4 additionally comprising: a shutter member to close said hopper portion during replacement of toner supply operations; and interlock means to prevent opening of said shutter member during said toner supply replacement operation.
 8. The toner feeding apparatus according to claim 1 additionally comprising: means for deriving a signal proportional to the concentration of toner in said utilization device; and means for selectively controlling said drive means in response to said signal to maintain a predetermined concentration of toner in said utilization device.
 9. The toner feeding apparatus according to claim 1 additionally comprising: means for deriving a signal proportional to the concentration of toner in said utilization device; and speed control means for controlling the rotational speed of said drive means in response to said signal so that the quantity of said toner metered to said utilization device may be regulated accordingly.
 10. The toner feeding apparatus according to claim 4 additionally comprising: means for deriving a signal proportional to the concentration of toner in said developer unit; and means for selectively controlling said drive means in response to said signal to maintain a predetermined concentration of toner in said developer unit.
 11. The toner feeding apparatus according to claim 4 additionally comprising: means for deriving a signal proportional to the concentration of toner in said developer unit; and speed control means for controlling the rotational speed of said drive means in response to said signals so that the quantity of said toner metered to said developer unit may be regulated accordingly. 